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Diffstat (limited to 'proofsearch/src/search/prover.cc')
| -rw-r--r-- | proofsearch/src/search/prover.cc | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/proofsearch/src/search/prover.cc b/proofsearch/src/search/prover.cc new file mode 100644 index 0000000..f3f8bb0 --- /dev/null +++ b/proofsearch/src/search/prover.cc @@ -0,0 +1,167 @@ +/* + * richard-atp-engine: A saturation-based automated theorem prover for first-order logic. + * Copyright (C) 2026 Richard Qin + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +#include "atp/search/prover.h" + +#include "atp/core/clause.h" +#include "atp/core/clause_store.h" +#include "atp/core/term_bank.h" +#include "atp/core/types.h" +#include "atp/infer/resolution.h" +#include "atp/infer/unification.h" +#include "atp/simplify/subsumption.h" +#include "atp/simplify/tautology.h" + +#include <algorithm> +#include <cstddef> +#include <cstdint> +#include <optional> +#include <utility> +#include <vector> + +namespace atp { + +Prover::Prover(TermBank& bank, ClauseStore& store, ProverConfig config) + : bank_(bank), store_(store), config_(std::move(config)), unprocessed_(config_.comparator_) {} + +void Prover::addClauses(std::vector<Clause> clauses) { + for (auto& clause : clauses) { + clause.depth_ = 0; + ClauseId const id = store_.addClause(clause); + unprocessed_.push(store_.getClause(id)); + } +} + +bool Prover::hitResourceLimit(size_t iterations) const { + return iterations >= config_.max_iterations_ || store_.size() >= config_.max_clauses_; +} + +Clause Prover::popGivenClause() { + Clause given = unprocessed_.top(); + unprocessed_.pop(); + return given; +} + +bool Prover::isForwardSubsumedByProcessed(const Clause& clause) const { + return std::ranges::any_of(processed_, + [&](ClauseId pid) { return subsumes(store_.getClause(pid), clause); }); +} + +bool Prover::shouldSkipGiven(const Clause& given) const { + return isTautology(given) || isForwardSubsumedByProcessed(given); +} + +void Prover::applyBackwardSubsumption(const Clause& given) { + std::erase_if(processed_, [&](ClauseId pid) { return subsumes(given, store_.getClause(pid)); }); +} + +std::vector<Clause> Prover::generateNewClauses(const Clause& given) const { + std::vector<Clause> new_clauses; + const UnificationConfig uconfig{.enable_occurs_check_ = config_.enable_occurs_check_}; + + for (ClauseId const pid : processed_) { + const Clause& pc = store_.getClause(pid); + + auto resolvents1 = allResolvents(bank_, given, pc, uconfig); + auto resolvents2 = allResolvents(bank_, pc, given, uconfig); + + for (auto& r : resolvents1) { + new_clauses.push_back(std::move(r)); + } + for (auto& r : resolvents2) { + new_clauses.push_back(std::move(r)); + } + } + + auto factors = factor(bank_, given, uconfig); + for (auto& f : factors) { + new_clauses.push_back(std::move(f)); + } + + return new_clauses; +} + +uint16_t Prover::computeDepth(const Clause& clause) const { + uint32_t const d1 = (clause.parent1_ != kInvalidId) ? store_.getClause(clause.parent1_).depth_ : 0; + uint32_t const d2 = (clause.parent2_ != kInvalidId) ? store_.getClause(clause.parent2_).depth_ : 0; + return static_cast<uint16_t>(std::max(d1, d2) + 1); +} + +std::optional<ClauseId> Prover::processNewClauses(std::vector<Clause> new_clauses) { + for (auto& nc : new_clauses) { + if (nc.isEmpty()) { + return store_.addClause(std::move(nc)); + } + + if (isTautology(nc)) { + continue; + } + + nc.depth_ = computeDepth(nc); + + ClauseId const nid = store_.addClause(nc); + const Clause& stored_nc = store_.getClause(nid); + if (isForwardSubsumedByProcessed(stored_nc)) { + continue; + } + + unprocessed_.push(stored_nc); + } + + return std::nullopt; +} + +ProverResult Prover::prove() { + size_t iterations = 0; + + while (!unprocessed_.empty()) { + if (hitResourceLimit(iterations)) { + return ProverResult::kTimeout; + } + ++iterations; + + Clause given = popGivenClause(); + + if (given.isEmpty()) { + empty_clause_id_ = given.id_; + return ProverResult::kTheorem; + } + + if (shouldSkipGiven(given)) { + continue; + } + + applyBackwardSubsumption(given); + std::vector<Clause> new_clauses = generateNewClauses(given); + processed_.push_back(given.id_); + + const std::optional<ClauseId> derived_empty = processNewClauses(std::move(new_clauses)); + if (derived_empty.has_value()) { + empty_clause_id_ = derived_empty; + return ProverResult::kTheorem; + } + } + + return ProverResult::kSaturation; +} + +std::optional<ClauseId> Prover::getEmptyClauseId() const { + return empty_clause_id_; +} + +} // namespace atp
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